ok

Author: yglukhov

compiler/closureiters.nim

@@ -1316,28 +1316,19 @@ proc replaceInlinedStates(ctx: var Ctx, n: PNode): PNode =
     else:
       n[i] = ctx.replaceInlinedStates(c)
 
-proc deleteEmptyStates(ctx: var Ctx) =
-  # 1. Assign temporary indexes to state labels to facilitate
-  # countStateOccurences. Label number will correspond to index in
-  # ctx.states
+proc optimizeStates(ctx: var Ctx) =
+  # Optimize empty states away and inline inlinable states
+  # This step requires that unique indexes are already assigned to state labels
 
-  # for i in 0 .. ctx.states.high:
-  #   ctx.states[i].label.intVal = i
-
-  # 1. Delete empty states: go through ctx.states,
-  # if a state consists only of gotoState node, delete it from states
-  # and replace its label index to its target state
-
-  # var labelsToReplace = newSeq[(PNode, PNode, bool)]()
-
-  # Collect empty states
+  # Find empty states (those consisting only of gotoState node) and mark
+  # them deletable.
   for i in 0 .. ctx.states.high:
     let s = ctx.states[i]
     let body = skipStmtList(s.body)
     if body.kind == nkGotoState and body[0].kind == nkIntLit and body[0].intVal >= 0:
       ctx.states[i].deletable = true
 
-  # Delete empty states
+  # Replace deletable state labels to labels of respective non-empty states
   for i in 0 .. ctx.states.high:
     ctx.states[i].body = ctx.replaceDeletedStates(ctx.states[i].body)
 
@@ -1353,18 +1344,15 @@ proc deleteEmptyStates(ctx: var Ctx) =
   for i in 0 .. ctx.states.high:
     ctx.states[i].label.intVal = i
 
-  # 2. Count state occurences
+  # Count state occurences
   var stateOccurences = newSeq[int](ctx.states.len)
   for s in ctx.states:
     ctx.countStateOccurences(s.body, stateOccurences)
 
-  var statesToInline = newSeq[int]()
+  # If there are inlinable states refered not exactly once, prevent them from inlining
   for i, o in stateOccurences:
-    if o == 1 and ctx.states[i].inlinable:
-      discard
-    else:
+    if o != 1:
       ctx.states[i].inlinable = false
-      # statesToInline.add(i)
 
   # echo "States to optimize:"
   # for i, s in ctx.states:
@@ -1383,7 +1371,7 @@ proc deleteEmptyStates(ctx: var Ctx) =
     else:
       inc i
 
-  # Reassign state label indexes
+  # Reassign state label indexes one last time
   for i in 0 .. ctx.states.high:
     ctx.states[i].label.intVal = i
 
@@ -1484,8 +1472,7 @@ proc transformClosureIterator*(g: ModuleGraph; idgen: IdGenerator; fn: PSym, n:
   for i in 0 .. ctx.states.high:
     ctx.states[i].label.intVal = i
 
-  # Optimize empty states away
-  ctx.deleteEmptyStates()
+  ctx.optimizeStates()
 
   let caseDispatcher = newTreeI(nkCaseStmt, n.info,
       ctx.newStateAccess())